The present invention is directed to circuit interrupters, and more particularly to circuit interrupter operating mechanisms.
Circuit interrupter operating mechanisms are used to manually control the opening and closing of movable contact structures within circuit interrupters. Additionally, these operating mechanisms in response to a trip signal, for example, from an actuator device, will rapidly open the movable contact structure and interrupt the circuit. To transfer the forces (e.g., to manually control the contact structure or to rapidly trip the structure with an actuator), operating mechanisms employ powerful operating springs and linkage arrangements. The spring energy provided by the operating springs must provide a high output force to the separable contacts.
Commonly, multiple contacts, each disposed within a cassette, are arranged within a circuit breaker system for protection of individual phases of current. The operating mechanism is positioned over one of the cassettes and generally connected to all of the cassettes in the system. Because of the close position between each of the cassettes, and between each cassette and the operating mechanism, the space available for movable components is minimal. A typical problem is not having sufficient space to accommodate proper operating springs to generate sufficient energy to rapidly open the breaker contacts when the operating mechanism is tripped. Circuit breakers of the prior art have addressed this problem by increasing the size of the breaker to allow for a larger operating mechanism.
In an embodiment of the present invention, a circuit breaker operating mechanism for separating a pair of electrical contacts within an electrical circuit breaker includes a lower link operatively connected to one of the electrical contacts. The operating mechanism further includes an upper link having first and second legs extending from a central portion. The first leg is pivotally secured to the lower link, and the second leg includes a cam surface formed thereon. A roller is in intimate contact with the cam surface, and the cam surface is configured such that movement of the upper link relative to the roller causes the upper link to pivot about the central portion. Pivoting of the upper link about the central portion moves the lower link causing the second contact to move away from the first contact.
In an alternative embodiment of the present invention, a circuit breaker operating mechanism for separating a pair of electrical contacts within an electrical circuit breaker includes an operating spring configured to provide a force for separating the electrical contacts when the operating mechanism is tripped. The operating mechanism further includes an operating handle configured to reset the operating mechanism after the operating mechanism has been tripped. The operating handle includes a void disposed therein, and an end of the spring is secured to the operating handle within the void.